This application relates generally to the field of radioimmunoassay, and in particular to an automatic sample changer for carrying and testing a plurality of gamma ray emitting samples. The sample changer disclosed in the present application is an extension of that which is described in U.S. Pat. application Ser. No. 504,743, filed on Sept. 10, 1974, now abandoned, and copending continuation U.S. Pat. application Ser. No. 626,923, filed on Oct. 29, 1975, each having been assigned to the present assignee. The attention of the reader is directed to this copending patent application, the disclosure of which is incorporated herein.
In the above-noted copending patent application, there is disclosed an automatic sample changer which is capable of sequentially testing up to 100 samples. The samples are moved along a continuous track by a single indexing wheel, and are successively associated with an elevator mechanism which transports the respective samples from the plane of the track into the testing zone. This known sample changer is equipped with a mechanical mechanism for indicating the sample being tested, and a printing mechanism for permanently recording data generated during each test. Also provided in this known sample changer is a mechanism for indicating when the paper on the print-out roll becomes low.
It is the purpose of the present invention to expand the capabilities and to improve the performance of the automatic sample changer disclosed in U.S. Pat. application Ser. No. 626,923.